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avr.c
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1 /*
2  * AVR demuxer
3  * Copyright (c) 2012 Paul B Mahol
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 #include "libavutil/intreadwrite.h"
23 #include "avformat.h"
24 #include "internal.h"
25 #include "pcm.h"
26 
27 static int avr_probe(AVProbeData *p)
28 {
29  if (AV_RL32(p->buf) == MKTAG('2', 'B', 'I', 'T'))
30  return AVPROBE_SCORE_MAX / 2;
31  return 0;
32 }
33 
35 {
36  uint16_t chan, sign, bps;
37  AVStream *st;
38 
39  st = avformat_new_stream(s, NULL);
40  if (!st)
41  return AVERROR(ENOMEM);
42 
44 
45  avio_skip(s->pb, 4); // magic
46  avio_skip(s->pb, 8); // sample_name
47 
48  chan = avio_rb16(s->pb);
49  if (!chan) {
50  st->codec->channels = 1;
51  } else if (chan == 0xFFFFu) {
52  st->codec->channels = 2;
53  } else {
54  av_log_ask_for_sample(s, "unknown number of channels\n");
55  return AVERROR_PATCHWELCOME;
56  }
57 
58  st->codec->bits_per_coded_sample = bps = avio_rb16(s->pb);
59 
60  sign = avio_rb16(s->pb);
61 
62  avio_skip(s->pb, 2); // loop
63  avio_skip(s->pb, 2); // midi
64  avio_skip(s->pb, 1); // replay speed
65 
66  st->codec->sample_rate = avio_rb24(s->pb);
67  avio_skip(s->pb, 4 * 3);
68  avio_skip(s->pb, 2 * 3);
69  avio_skip(s->pb, 20);
70  avio_skip(s->pb, 64);
71 
72  if (!sign && bps == 8) {
74  } else if (!sign && bps == 16) {
76  } else if (sign == 0xFFFFu && bps == 8) {
78  } else if (sign == 0xFFFFu && bps == 16) {
80  } else {
81  av_log_ask_for_sample(s, "unknown bits per sample\n");
82  return AVERROR_PATCHWELCOME;
83  }
84 
85  st->codec->block_align = bps * st->codec->channels / 8;
86 
87  avpriv_set_pts_info(st, 64, 1, st->codec->sample_rate);
88  return 0;
89 }
90 
92  .name = "avr",
93  .long_name = NULL_IF_CONFIG_SMALL("AVR (Audio Visual Research)"),
94  .read_probe = avr_probe,
95  .read_header = avr_read_header,
96  .read_packet = ff_pcm_read_packet,
97  .read_seek = ff_pcm_read_seek,
98  .extensions = "avr",
99  .flags = AVFMT_GENERIC_INDEX,
100 };